During drilling of wells, it may be desirable to cement the casing in the wellbore in separate stages. For instance, problems during cementing such as lost circulation, sustained casing pressure from gas migration, water pressure, high-pressure gas zones and other issues may make two-stage cementing useful. In certain traditional processes, a two-stage cementing tool may be placed in the casing or between joints of casing at one or more locations in the wellbore. Cement may be flowed through the bottom of the casing and up the annulus to the lowest cementing tool. The lowest cementing tool may close off the bottom. The cementing tool may be opened, and cement flowed through the cementing tool up the annulus to the next-most upper stage. This process may be repeated until stages of cementing the well are completed.
Downhole tools used in a wellbore may be ball, dart, or plug actuated. A ball, dart, or plug may be pumped through the wellbore to engage with a landing seat on the downhole tool to activate the tool. Typical landing seats extend into the interior of the bore of the downhole tool and may restrict or reduce flow or ability of other tools to pass therethrough.